Wellbores drilled for hydrocarbon extraction involve a series of assembly and testing steps before hydrocarbon production may begin. One step requires testing to ensure the integrity of cement used to seal the wellbore casing to the surrounding rock formation. This cement seal prevents communication between producing zones, acquifiers, and any contamination related thereto. Integrity testing traditionally involves water shut-off tests, formation integrity tests, and cement bond logs. Traditional integrity testing means and methods, such as cement bond logs, while generally effective are of significant cost and complexity.
Various efforts have been made to significantly improve wellbore cementing operations. For example, U.S. Pat. No. 6,679,336 to Musselwhite et al. (“Musselwhite”) issued Jan. 20, 2004 discloses a float shoe/collar apparatus and method for multi-purpose use in running a tubular string such as a casing string or liner into a wellbore and for optimizing cementing operations. In one embodiment, the apparatus permits auto filling of the tubular string as the string is lowered into the wellbore. Circulation can be effected through down jets for washing the wellbore as necessary. After the tubular string is positioned, the down jets can be blocked off and up jets opened to thereby direct cement upwardly to optimize cement placement. Check valves can also be activated to prevent flow from the wellbore into the tubular string. The apparatus comprises an inner member and tubular member. The inner member is movable upon release of shear pins to cause longitudinal movement relative to the outer member. The movement of the inner member may close a plurality of downward jets and may also open a plurality of upward jets. The apparatus may also be equipped with a set of check valves which can be held open on run in, and subsequently activated to thereby automatically close upon cementing to prevent “u-tubing” of fluid from the annulus back into the casing or other tubing string. However, Musselwhite does not disclose a testing assembly comprising a frangible body and a tool body, the tool body providing a passageway to the annular seal when the frangible body is drilled out. Musselwhite is incorporated herein by reference in its entirety.
European Patent No. EP0489816 to Mueller et al. (“Mueller”) issued Jun. 17, 1992 and discloses a ported float shoe and a landing collar attached at a first end of a portion of a casing string and a sliding air trapping insert attached at the other end. The air trapping insert includes a fluid flow passageway blocked by a plug attached by shear pins to the insert or having a conduit providing a fluid passageway to the first end. The air trapping insert and float shoe form an air cavity within the string portion. The air cavity provides buoyant forces during running, cementing or other casing operations within a borehole, reducing running drag and the related chance of a differentially stuck casing. However, Mueller does not disclose a testing assembly comprising a frangible body and a tool body, the tool body providing a passageway to the annular seal when the frangible body is drilled out. Mueller is incorporated herein by reference in its entirety.
U.S. Pat. No. 2,120,694 to Crowell (“Crowell”) issued Jun. 14, 1938 discloses a means for cementing oil wells, principally to shut out water, as well as to support and protect the casing. Crowell discloses a specialized valve to perform three functions; a float valve to float the casing in, as part of a cementing plug to actuate valve means to open lateral ports through the wall of the casing, and to close the bore through the casing below said lateral port and thus deflect the cementing mixture there-through. Crowell does not disclose a testing assembly comprising a frangible body and a tool body, the tool body providing a passageway to the annular seal when the frangible body is drilled out. Crowell is incorporated herein by reference in its entirety.
U.S. Pat. No. 2,735,498 to Muse (“Muse”) issued Feb. 21, 1956 discloses a subsurface well bore apparatus adapted to form part of a conduit string, such as a casing, liner or drill pipe string, as it is lowered through fluid in the well bore. Muse does not disclose a testing assembly comprising a frangible body and a tool body, the tool body providing a passageway to the annular seal when the frangible body is drilled out. Muse is incorporated herein by reference in its entirety.
U.S. Pat. No. 3,768,562 to Baker (“Baker”) issued Oct. 30, 1973 discloses a full opening cementing tool suitable for cementing an oil well Baker utilizes a cylindrical housing, a sliding valve sleeve within the housing, and an opening positioner and a closing positioned located on a pipe string within the casing for actuating the sliding valve sleeve. Other tools such as isolation packers and circulating valves may be used in conjunction with one or more of the cementing tools. Baker does not disclose a testing assembly comprising a frangible body and a tool body, the tool body providing a passageway to the annular seal when the frangible body is drilled out. Baker is incorporated herein by reference in its entirety.
U.S. Pat. No. 4,132,111 to Hasha (“Hasha”) issued Jan. 2, 1979 discloses a body having a longitudinal opening provided with longitudinally spaced, annular seal means. The body is provided with passage means for conducting fluid to move the seal means radially of the body opening to seal against tubular members in the body opening. The tubular members are connected together by suitable means such as a coupling, weld, or other arrangement prior to positioning the connection between the seal means. After the seal means has sealed off the connection there between, the body includes additional passage means for conducting fluid pressure to increase the fluid pressure externally of the connection to a pressure significantly greater than the internal pressure to externally test the connection by instrumentally or visually detecting any resultant inflow of the pressurized external fluid. Where the method is employed for leak testing a thread-connected, multiple seal pipe joint having at least one internal and at least one external sealing arrangement, the connection between the tubular members may be only partially made up to a predetermined condition at which a primary or initial internal seal is established in the connection without engaging the external seal. After the joint has been externally tested in this condition, the test seals may be withdrawn from the tubular member and the connection completed to full make-up torque, and the joint again externally sealed and fluid pressure applied to externally test the connection. Hasha, however, does not disclose a testing assembly comprising a frangible body and a tool body, the tool body providing a passageway to the annular seal when the frangible body is drilled out. Hasha is incorporated herein by reference in its entirety.
U.S. Pat. No. 4,694,903 to Ringgenburg (“Ringgenberg”) issued Sep. 22, 1997 discloses a tubing tester valve of the present invention comprises a tubular housing assembly having a downwardly closing, spring biased flapper valve. A tubular mandrel assembly is disposed within the housing assembly below the flapper valve, and is secured to the housing assembly with shear pins. The tubing tester valve may be permanently opened through the application of annulus pressure from the rig floor to the annulus surrounding the pipe string, which pressure moves the mandrel assembly upward to rotate the flapper valve to an open position. In order to assure that the mandrel assembly does not retract downwardly, thus permitting the flapper valve to reclose, a spring biased locking means is provided to hold the mandrel assembly in its “up” position. However, Ringgenberg does not disclose a testing assembly comprising a frangible body and a tool body, the tool body providing a passageway to the annular seal when the frangible body is drilled out. Ringgenberg is incorporated herein by reference in its entirety.
U.S. Pat. No. 6,401,824 to Musselwhite, et al. (“Musselwhite”) issued Jun. 11, 2002 discloses an improved float shoe/collar apparatus is provided for use during casing run in or floated in. The apparatus has an inner tubular member and outer tubular member, movable upon release of shear pins to cause longitudinal movement relative to each other. The movement of the inner tubular member closes a plurality of downward jets and opens a plurality of upward jets. The apparatus also is equipped with a set of check valves, held open on run in, and activated to close upon cementing to prevent “u-tubing” of fluid back into the casing. Musselwhite does not disclose a testing assembly comprising a frangible body and a tool body, the tool body providing a passageway to the annular seal when the frangible body is drilled out. Musselwhite is incorporated herein by reference in its entirety.
What is needed is an apparatus and method for testing the sealing integrity of wellbores, and particularly an apparatus and method to efficiently and effectively test the annular seal of a tubular string positioned within a wellbore. In one embodiment of the invention, an apparatus and method are disclosed which allow direct testing of the hydraulic annular seal of casing without the use of a cement bond log (“CBL”). In one embodiment, surface casing could be tested for an annular seal in a fraction of the time and expense of the use of cement bond logs. It has been estimated in a report for the Western Energy Alliance that proposed cement bond log regulations by the BLM would cost over $140,000 per well in direct costs and lost rig time. In contrast, the use of one embodiment of the present invention could test the seal of the annulus of a casing for a fraction of this cost.